Silk screen printing machine



April 14, 1959 J. E. PODGOR SILK SCREEN PRINTING MACHINE Filed March 6,1957 2 Sheets-Sheet 1 INVENTOR. JnsEPH E. P01351112 April 14, 1959 J. E.PODGOR SILK SCREEN PRINTING MACHINE 2 Sheets-Sheet 2 Filed March 6, 1957INVENTOR.

United States Patent SILK SCREEN PRINTING MACHINE Joseph E. Podgor,Philadelphia, Pa. Application March 6, 1957, Serial No. 644,255

2 Claims. (Cl. 101-126) My invention relates to a silk screen processprinting machine, and, more particularly relates to a ballast system forthe squeegee and printing frame wherein the printing of large quantitiesof sheets may be greatly accelerated.

The silk screen printing process utilizes a sheet of fabric screen whichis stretched tightly upon a frame and has a stencilled portion throughwhich paint may pass to form the design. Paint in a semi-liquid State isplaced upon the stencilled screen at one end thereof and is drawntherefrom in a wave by a squeegee scraper. The paint thus drawn from thestencil fills the open pores of the pervious design portion of thestencil and adheres to the sheet to be imprinted.

The class of work turned out by apparatus of this description competesproductionwise with other printing processes. However, since silk screenprinting machines are hand operated, it is necessary for the squeegeeassembly, as well as the printing frame, to be easily manipulated sothat the operator may turn out a large quantity of work without unduestrain in setting up the work sheets in sequence. While prior silkscreen machines utilize balanced ballast systems, each of these wereeither expensive in manufacture or appeared clumsy with overhangingpulley systems.

It is, therefore, an object of my invention to provide a silk screenprinting machine wherein the printing frame and squeegee assembly areuniformly balanced in all positions of the stroke or lifting operations.

Another object of my invention is to provide a silk screen printingmachine that easily permits adjustment for any size printing frame.

Another object of my invention is to provide a carriage for the squeegeeassembly wherein the suspension enables balanced manipulation during thestroke and lifting operations.

Another object of my invention is to provide a silk screen processprinting machine wherein a minimum of pulley encumbrances are presented.

Another object of my invention is to provide a silk screen processprinting machine wherein means are afforded to lift the squeegeeassembly and printing frame simultaneously at the end of the stroke ineach direction.

Another object of my invention is to provide a silk screen processprinting machine wherein accurate registration of the printed matter isavailable for stroke in either direction.

Other objects of my invention are to provide an improved device of thecharacter described, that is easily and economically produced, which issturdy in construction, and Which is highly efiicient in operation.

With the above and related objects in view, my invention consists in thedetails of construction and combination of parts, as will be more fullyunderstood from the following description, when read in conjunction withthe accompanying drawing, in which:

Fig. 1 is a rear perspective view of a silk screen process printingmachine embodying my invention.

Fig. 2 is a side view of the silk screen printing machine showing theframe in lifted position at the end of the stroke of the squeegeeassembly.

Fig. 3 is a fragmentary view showing the hinged brackets for theprinting frame.

Fig. 4 is an enlarged view showing the details of the carriagesuspension.

Fig. 5 is a sectional view taken along lines 5-5 of Fig. 4.

Fig. 6 is a sectional view taken along lines 6-6 of Fig. 3.

Referring now in greater detail to the drawing in which similarreference characters refer to similar parts, I show a silk screenprocess printing machine comprising a table, generally designated as A,a printing frame mounting, generally designated as B, and squeegeeassembly and suspension, generally designated as C, and a ballastbalancing system, generally designated as D.

The printing table A is of conventional design having a surface top 10supported upon four legs 12. It is upon the surface top 10 which theprinting material 14 is placed directly below the frame assembly B.

The frame assembly B, comprises a stencilled screen 16, which isstretched tautly within a wooden frame border 18, the latter beinghinged at its rearward portion to a pair of brackets B1 supported upon alongitudinally extending angle bar 20 at the back of the surface top 10.Each bracket B1 comprises a slotted member 22 and a clamp 23 pivotallyconnected to each other about a horizontal axis by a hinge 24. Themember 22 is adjustably secured through its elongated slot to the anglebar 20 at one of a plurality of tapped holes 25 therein by passing thethreaded end of a knurled stud 26 through the slot for threadedengagement with one of the tapped holes. This enables forward orrearward adjustment of the brackets B1 upon the table top. The slotmember 22 is also pivotally connected about a vertical axis to the hinge24 by a swivel bolt 27. Each clamp 23 comprises a plate 28 having a pairof apertured bosses 29 therein and a block 30, the block having athreaded stud 32 extending from one face thereof. The clamp 23 issecured to the rear of the painting frame 18 by passing the stud 32through one of the holes 29 in the plate 28 and tightening a knurledknob 34 upon the threaded end of the stud 32. Thus, the printing frame18 may be embraced by the clamp 23, and laterally positioned between theplate 28 and the block 30. It is thus to 'be noted that the printingframe assembly B has infinite degrees of freedom whereby any sizeprinting frame 18 may be secured upon the table A and suitableadjustment being made in the bracket B1 to accommodate adjustment in anyone of three planes.

A traverse rail 38, circular in cross section, is longitudinallysupported immediately above the block 20 by a pair of supports 40 at itsend points. Immediate inboard of supports 40, are a pair of arms 42,rotatably and slid ably supported upon the track 38 by a bearing 43, oneend of each arm having a chain and snap fastener 44 which mounts on aneyelet secured upon each side of the printing frame 18. The other end ofeach arm 42 overhangs the back of the table A and each is connected tothe pulley ballast system D, which will be described in greater detailhereinafter. It is also to be observed that each arm 42 at its rearwardportion thereof has an inwardly extending member 46 mounted thereon,these arms detachably engaging the squeegee assembly C at the end of itsstroke in either direction whereby lifting the squeegee willsimultaneously raise the printing frame assembly B to the hinge bracketsB1.

The arms 42 are each rectangular tubes having a plurality of spacedholes 45 longitudinally extending along the bottom surface thereof. Thebearings 43 are mounted th ou h any pair oi the holes 45 hereby thelength of the arms 42 may be adjusted to compensate for different widthprinting frames. As set forth above, the bearings 43 are also slidablymounted upon the track 38 in order to permit adjustment for differentlengths of printing frames. Suitable rubber grommets 47 are slidablymounted upon the track 38 inboard of the arms 42. The grommets 47'frictionally engage the track 38 and restrict further movement of thearms 44 toward each other after the latter have been positioned for aparticular length printing frame.

The squeegee assembly C comprises a lever arm as,

which is slidably and hingedly supported upon the traverse rail 38 by acarriage suspension C1. A squeegee blade or scraper 50 is mounted uponthe bottom of the lever arm 48'and adjustably secured thereto. The car ie S p ns on 01 omp ses a p i p s 2 and 54,. each end of which has a setof roller bars 56 con sisting of three rollers mounted. 120 apart fromeach other about the traverse rail 38. Thus the rollers 56 securelyembrace the traverse rail 38 and enable the lever arm 48 tolongitudinally slide along the table surface and permit pivotal raisingof the lever arm in a plane at right angles to the table surface at anytime. Therearward end of the lever arm 48 overhangs the back of thetable A and has a ballast weight 58 adjustably mounted thereon to securebalancing of the squeegee assembly about its fulcrum. In the middle ofits stroke, the squeegee assembly C is independent of the frame assemblyB. However, at each end of its stroke, the squeegee assembly C permitsengagement immediately above the inwardly turned member 46, wherebyraising the forward end of the lever arm 48 will depress the rear of thearms 42 and cause the printing frame B to raise upwardly.

The pulley ballast system D is mounted solely to the printing frameassembly B through the arms 42 and do not co-act with the squeegeeassembly C except at the end of its stroke when the lever arm 48 israised. However, uniform balancing in any position is provided since theeffective moment of the squeegee assembly is zero. The pulley ballastsystem D comprises a coil spring 60 which has a cord 62 mounted at eachend thereof and extending through a pulley 64. secured to the back ofthe table. The cord 62 passes through each pulley 64 and extendsdownwardly through a pulley 66 secured upon the lower rear end of thetable. The free end of each cord 62 then passes upwardly and is mountedupon an adjusting block 68 through a pair of holes therein. An adjustingcord 70 is also looped at one end through the upper hole of theadjusting block 68, the upper end ofthe cord 70 being secured to therear of the arm 42. Looping the cord 7 0 through the block 68 permitsminute adjustment of the pulley system D by convenientlydraw! ingtension on the coil spring 60 to, suit the balance of the printing frameassembly at any time.

As is, apparent from the foregoing description, balancing the tension ofthe coil. spring properly will permit the printing frame assembly B tobe set in any vertical hinged position without falling or raising due toits functional adjustment of the pulley system B. As the squeegee isdrawing longitudinally across the table and the scraper 50 hearingdownward On the screen 16, the printing frame will remain fiat upon theprinted sheet. At the end of the stroke, raising the lever arm 48 willcause lifting of the frame from the table top because of the engagementof the lever arm with the inwardly turned rods 46. Thus it is seen thatsimultaneous lifting of the frame may be accomplished when the squeegeeis at the end of its stroke. By raising the lever arm about the wave ofsurplus ink and then lowering the lever arm on the opposite sidethereof, the squeegee assembly is now in position to stroke in theopposite direction across the stencil 16 after the new work sheet hasbeen placed in its proper position el the f ame 1.8-

Although my invention has been described in considerable detail, suchdescription is intended as being illustrative rather than limiting,since the invention may be variously embodied, and the scope of theinvention is to be determined as claimed.

I claim as my invention:

1. A silk screen process printing machine comprising a table, a printingframe assembly having a screen thereon, and a ballast system, said frameassembly being hingedly secured upon the back of said table by a pair ofhinge brackets, a pair of arms pivotally and slidably secured to atraverse rail on the back of said table, the forward end of each of saidarms being detachably connected to said printing frame assembly and therear end of each of said arms overhanging the rear of said table, saidballast system comprising a coil spring having a cord attached to eachend thereof and mounted to the back of said table through a series ofpulleys, the outboard end of each of said cords being secured to theoverhanging end of one of said arms, a squeegee assembly slidably and,hingedly mounted upon said rail and an inwardly turned member secured tothe rear end of each of said arms, each of said members being engaged bysaid squeegee assembly at each end respectively of the stroke thereof,whereby raising said squeegee assembly will raise said printing frame.

2. The silk screen printing frame of claim 1 wherein said rail comprisesa rod circular in cross section, said squeegee assembly having two setsof bearings therein embracing said rail, each set of bearings comprisingthree roller bearings mounted apart from each other upon said track.

References Cited in the file of this patent UNITED STATES PATENTS allm

